This application is based upon Japanese Patent Application No. 2001-173931, filed on Jun. 8, 2001, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an air conditioner for a vehicle, which has an electric-powered hot water pump as an apparatus for circulating hot water in a heater core for heating, and is especially suitable for actuation control of the electric-powered hot water pump in a hybrid (gas-and-electric powered) vehicle, an economical running vehicle or the like.
2. Related Art
An air conditioner for a hybrid vehicle which is driven by an engine and an electric motor is disclosed in JP-A-10-236145. The air conditioner has a hot water circuit in which hot water (coolant) of the engine is circulated in the heater core by a mechanical hot water pump driven by the engine while the engine is activated, and by an electric-powered hot water pump while the engine is not activated.
Moreover, the air conditioner detects a position of an air mix door for adjusting the ratio between air mass flow (the amount of cool air) passing through a bypass passage of the heater core and air mass flow (the amount of hot air) passing through the heater core. The air conditioner does not heat air by the heater core, and deactivates the electric-powered hot water pump, even if the engine is not activated, when the air mix door is positioned at a maximum cooling position (door opening degree=0) which indicates air mass flow is prohibited from passing through the heater core.
This means, in this conventional air conditioner, the electric-powered hot water pump is always activated when the air mix door is not positioned at the maximum cooling position during non-activation of engine. As a result, electrical power consumption involved in activation of the electric-powered hot water pump increases while the engine is not activated, thereby hastening deterioration of the remaining charge in the battery mounted on the vehicle.
An object of the invention is to provide an air conditioner for a vehicle that has an electric-powered hot water pump as an apparatus for circulating hot water in a heater core, and that can reduce electric power consumption involved in the actuation of the electric-power hot water pump.
According to an aspect of the present invention, the air conditioner has a controller for controlling the electric-powered hot water pump which determines whether the amount of conserved heat in the heater core satisfies the amount of heat required for heating air. The controller stops the activation of the electric-powered hot water pump when the amount of conserved heat is determined to satisfy the amount of necessary heat. As a result, the electrical power consumption can be reduced when the amount of conserved heat is presumed to satisfy the amount of heat necessary.
According to a second aspect of the present invention, a temperature adjusting means for adjusting the temperature of air blown into a passenger compartment of the vehicle by adjusting the amount of heating of the air heated by the heater core, and a calculating means for calculating a threshold value (xcex8xcex1) for determining a position of the temperature adjusting means based on information in association with the amount of conserved heart in the heater core are provided. This determines that the amount of conserved heat in the heater core satisfies the amount of heat necessary for heating air when the temperature adjusting means is positioned within a lower-temperature side as compared to the threshold value (xcex8xcex1) for the operated position of the temperature adjusting means.
With these features, it can be suitably presumed whether the amount of conserved heat in the heater core for heating satisfies the amount of necessary heat for heating air by comparing the threshold value and the operated position of the temperature adjusting means.
Preferably, the calculating means shifts the threshold value to a value at a high temperature side in accordance with an increase of information which relates to the amount of conserved heat in the heater core, so that the amount of conserved heat in the heater core is better determined based on the change in information relating to the amount of conserved heat.
According to another aspect of the present invention, in addition to a mechanical hot water pump driven by the engine of the vehicle while the engine is activated, which circulates hot water in a hot water circuit, an air conditioner for the vehicle has a heater core provided in the hot water circuit for heating air blown out to a passenger compartment of the vehicle, an electric-powered hot water pump for circulating the hot water in the heater core while the engine is not activated, and a calculating means for calculating a non-active time period(txcex1) in which the electric-powered hot water pump can be stopped based on information in association with the amount of conserved heat in the heater core for heating when the status of the engine for the vehicle changes from activation to non-activation. In this air conditioner, when the status of the engine of vehicle changes from activation to non-activation, the electric-powered hot water pump is kept non-active during the non-active time period(txcex1). After the non-active time period(txcex1) has passed, the electric-powered hot water pump is activated.
Thus, even after the engine of the vehicle is stopped, the electric-powered hot water pump is kept non-active during the non-active time period, and therefore, activation time of the electric-powered hot water pump can be shortened. As a result, electrical power consumption by the electric-powered hot water pump can be reduced.
Preferably, the information relating to the amount of conserved heat of the heater core is specifically the temperature of the heater core.
Preferably, the temperature of the heater core can be determined based on the temperature of air sucked into the heater core, the temperature of the hot water and the air mass flow of the air.
According to another aspect of the present invention, in addition to a mechanical hot water pump driven by the engine of the vehicle while the engine is activated, which circulates hot water in a hot water circuit, an air conditioner for the vehicle has a heater core provided in the hot water circuit for heating air blown out to a passenger compartment of the vehicle, an electric-powered hot water pump for circulating the hot water in the heater core while the engine is not activated, and a temperature adjusting means for adjusting the temperature of air blown into a passenger compartment of the vehicle by adjusting the amount of heating of air heated by the heater core. In this air conditioner, the electric-powered hot water pump is kept non-active in a situation where the temperature adjusting means is positioned in a low-temperature side in comparison with a predetermined value(xcex81), and the lapsed time(t) is within a predetermined time(t1), after the status of the engine of vehicle changes from activation to non-activation. Also, the electric-powered hot water pump is activated in a situation where the temperature adjusting means is positioned in a high-temperature side in comparison with the predetermined value(xcex81), and the lapsed time(t) exceeds the predetermined time(t1), after status of the engine of vehicle changes from activation to non-activation.
Thus, the electric-powered hot water pump can be kept non-active by determining a situation where the amount of conserved heat of the heater core satisfies the amount of heat necessary based on the operated position of the temperature adjusting means and the lapsed time(t) after the engine of the vehicle is stopped. Therefore, activation time of the electric-powered hot water pump can be shortened. As a result, electrical power consumption by the electric-powered hot water pump can be reduced.
Preferably, the predetermined value(xcex81) is shifted to the high temperature side according to the increase of temperature of air sucked into the heater core, so as to appropriately set the predetermined value(xcex81) according to the change in the temperature of the sucked air.
Preferably, the predetermined time(t1) is lengthened in accordance with the increase of temperature of air sucked into the heater core for heating, so as to appropriately set the predetermined time (t1) according to the change in the temperature of the sucked air.
Preferably, the air conditioner further comprises an inside/outside air switching door for switching air-suction openings between inside and outside, and determines the temperature of the sucked air based on an operated position of the inside/outside air switching door, the temperature of inside air and the temperature of outside air.
Preferably, the predetermined time(t1) is lengthened in accordance with the increase of temperature of hot water at the time when the status of the engine changes from activation to non-activation, so as to appropriately set the predetermined time(t1) according to the change in the temperature of the hot water.
Other features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings.